KR20070115551A - N-Zi Image Image Data Encoding / Decoding Apparatus and Method - Google Patents

Abstract

An apparatus and a method for encoding/decoding N-bit image data are provided to change a hardware specification minimally in AVS(Audio and Video coding Standard), encode the N-bit image data, and simultaneously improve coding efficiency. The first adder(112) generates differential data in which predictive data of inputted image data are subtracted from the inputted image data. A transform and quantization unit(113) transforms a domain of the generated differential data into a frequency domain. The transform and quantization unit(113) quantizes the transformed differential data in response to bit depth indicating the accuracy of the inputted image data.

Description

A method and apparatus for encoding / decoding of N-bit video data}

1 is a block diagram illustrating a configuration of an audio and video coding standard (AVS) encoder according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a more detailed configuration of the transform and quantization unit 113 shown in FIG. 1.

3 is a flowchart illustrating an operation of the transform and quantization unit 113 according to an embodiment of the present invention.

4 is a block diagram showing the configuration of an AVS decoder according to an embodiment of the present invention.

5 is a block diagram illustrating a more detailed configuration of the inverse transform and inverse quantizer 414 shown in FIG. 4.

6 is a flowchart for describing an operation of the inverse transform and inverse quantization unit 414 according to an embodiment of the present invention.

7 is a graph comparing the coding efficiency according to the prior art and the embodiment of the present invention using a peak signal-to-noise (PSNR).

The present invention relates to image processing technology, and more particularly, to a method and apparatus for encoding and decoding image data having various bit depths of 8 bits or more.

In video communication systems and devices, there is a growing demand for large screens and hence high resolution. In the electronics market, consumer demand for large CRTs, LCDs, PDPs and high-definition projectors (TVs) is increasing. Moreover, the spread of image data processed and stored digitally such as MPEG, DVD, DV, and the like is accelerating this further. Accordingly, improving the image quality of the image or dynamic effect displayed on a large screen with high resolution has emerged as a very important problem.

In terms of the video encoding apparatus, the image quality of the displayed image is affected by the number of bits representing the image data value. This is because the bit depth representing the precision of the image data, that is, the number of bits representing the image data value increases, so that the data can be represented at various levels.

However, according to the conventional audio and video coding standard (AVS), the conventional encoding apparatus performs encoding only on data having a constant bit depth, such as 8 bit data. However, as the video compression technology develops, it is necessary to process data having a higher bit depth such as 10 bit or 12 bit or more according to the type of input video data or the demand of high definition display application. The performance of the encoding device that can be required. However, increasing the specification of the hardware to process data with higher bit depths is undesirable because it causes a price increase. Therefore, in the coding apparatus and method according to the AVS, it is necessary to improve the image quality of the displayed image data by encoding N bit image data having various bit depths while maintaining the same hardware specification.

The technical problem to be solved by the present invention, in the audio and video coding standard (AVS), the encoding of the N (integer or greater) bit image data can be encoded with a minimum change of hardware specifications, and at the same time the encoding efficiency is improved It is to provide a method and apparatus.

Another technical problem to be solved by the present invention is to provide a decoding method and apparatus which can decode N (integer of 8 or more) bit image data by changing a minimum of a hardware specification in an audio and video coding standard (AVS). will be.

In order to solve the above technical problem, the encoding method of the N-bit image data according to the present invention comprises the steps of (a) generating the difference data from the prediction data of the image data from the input image data (b) the difference And converting the data into a frequency domain and (c) quantizing the transformed differential data corresponding to a bit depth indicating the precision of the image data. (D) The bit depth (N). The method may further include generating and outputting a bitstream by encoding information about the quantized result.

In addition, step (c) is a step of quantizing the transformed differential data by performing a predetermined operation using predetermined coefficients determined according to the bit depth N, and (c1) converting the transformed differential data to a first predetermined value. Dividing by value; (c2) multiplying a result of dividing by the first predetermined value by a predetermined coefficient s; (c3) dividing a result of multiplying the predetermined coefficient s by a second predetermined value; (c4) multiplying a result of dividing by the second predetermined value by a predetermined coefficient q; And (c5) adding a predetermined value k to a result of multiplying the predetermined coefficient q and shifting the result of adding the predetermined value k to the right of the predetermined bit.

In addition, the bit depth N is preferably an integer of 8 or more.

In order to solve the above another technical problem, an apparatus for encoding N-bit image data according to the present invention includes a difference data generator for generating difference data from which prediction data of the input image data is removed from the input image data. And a conversion unit for converting the difference data into the frequency domain, and a quantization unit for quantizing the converted difference data corresponding to a bit depth indicating the precision of the input image data. The apparatus may further include an entropy encoder configured to generate and output a bitstream by encoding the information about the bit depth N and the quantized result.

The quantization unit may further include a first divider that divides the transformed difference data into a first predetermined value, a first multiplier that multiplies a result of dividing the converted difference data by the first predetermined value, and multiplies a result of the predetermined coefficient s A second division unit for dividing by a predetermined value, a second multiplier for multiplying a result of dividing by the second predetermined value, and a result of multiplying the predetermined coefficient q, and a result of adding the constant k to the result of multiplying the predetermined coefficient q, and adding the constant k And a shifting unit for shifting bits to the right, wherein the first and second predetermined values are values determined corresponding to the bit depths N, and the operations performed by the first and second division units are integer operations. It is preferable.

In addition, the bit depth N is preferably an integer of 8 or more.

In order to solve the another technical problem, the decoding method of the N-bit image data according to the present invention (a) a bit depth (N) indicating the precision of the image data included in the bit stream by decoding the input bit stream Restoring information about the quantized data and (b) dequantizing the reconstructed quantized data corresponding to the bit depth, and (c) inversely converting the dequantized result into a time domain to perform the inverse on the image data. And restoring difference data from which prediction data of the image data has been removed, and (d) restoring and outputting the image data by adding the predicted data of the image data to the restored difference data. can do.

In addition, step (b) includes (b1) multiplying the reconstructed quantized data by a predetermined coefficient r and (b2) dividing a result of multiplying the predetermined coefficient r by a predetermined coefficient n, and (b2) Is preferably performed by an integer operation.

In addition, the bit depth N is preferably an integer of 8 or more.

In order to solve the another technical problem, the decoding apparatus for N-bit image data decodes the input bitstream to restore the information about the bit depth and the quantization data representing the precision of the image data included in the bitstream An entropy decoder, an inverse quantizer for inversely quantizing the recovered quantized data corresponding to the recovered bit depth, and an inverse transformer for restoring the differential data by inversely transforming the inverse quantized result into a time domain.

The inverse quantization unit may include a third multiplier for multiplying the restored quantized data by a predetermined coefficient r, and a third divider for dividing a result of multiplying the predetermined coefficient r by a predetermined coefficient n, and performed by the third divider. The operation is preferably an integer operation.

In addition, the bit depth N is preferably an integer of 8 or more.

In order to solve the another technical problem, a computer-readable recording medium having a program for executing the encoding method and the decoding method according to the present invention on a computer is provided.

Hereinafter, with reference to the accompanying drawings and embodiments will be described a preferred embodiment of the present invention. The present invention is not limited to the embodiments described below, and various changes can be made by those skilled in the art from the appended claims, and such conversions fall within the scope of the present invention.

Moving image data is encoded / decoded by a motion prediction technique. Motion prediction is performed with reference to past frames or both past and future frames. When encoding / decoding a current frame, the frame referred to is referred to as a reference frame. In block-based video encoding, a still image or still frame constituting a video is generally divided into macroblocks (MB) of 16 ㅧ 16 units, and macroblocks are subblocks of smaller units. Divided into Thus, the motion between still images is predicted as block to block and encoded.

Hereinafter, an apparatus and method for encoding N-bit image data according to the present invention will be described with reference to FIG. 1.

FIG. 1 is a block diagram illustrating a configuration of an apparatus for encoding N-bit image data according to an embodiment of the present invention. The divider 100, the predictor 110, the first adder 112, and the encoding controller ( 120, a transform and quantization unit 113, and an entropy encoding unit 130.

When raw data having an 8-bit bit depth is input, the divider 100 selects a frame or field to be encoded according to the control of the encoding controller 120, and selects each selected angle. Split a frame or field into macro blocks. Each macro block is composed of 16 x 16 pixels. The macroblock of 16x16 pixels is composed of a plurality of 16x16 blocks and / or a plurality of 8x8 blocks that contain luminance or color difference information of the image data.

The encoding controller 120 extracts information about the bit depth N representing the precision of the input image data, and controls the overall operation of the encoding apparatus.

The first adder 112 receives the raw data output from the divider 100 and the prediction data predicted by the intra prediction module 117 or the inter prediction module 118. The differential data (X, differential data) is output by subtracting the prediction data from the raw data.

The transform and quantization unit 113 transforms the differential data X into an integer DCT (Discrete Cosine Transform) and quantizes the transformed differential data X to generate quantized data. The generated quantized data is output to the predictor 110.

The prediction unit 110 includes an inverse transform and inverse quantizer 114, a second adder 111, a deblocking unit 115, a memory 116, an intra-frame prediction unit 117, and inter-frame prediction. An inter prediction module 118 and a motion estimation unit 119 are included.

The inverse transform and inverse quantization unit 114 performs inverse integer DCT transform and inverse quantization on the quantized data output from the transform and quantization unit 113 to generate and output the recovered differential data X.

The second adder 111 adds the predicted data predicted by the intra-frame predictor 117 or the inter-frame predictor 118 to the reconstructed difference data X of the current frame, and decodes the result. Will output

The deblocking unit 115 performs filtering on each restored macroblock in order to reduce block distortion, and outputs each result of the filtering to the memory 116.

The memory 116 stores the data output from the deblocking unit 110 for later use by the intra-frame predictor 117 or the inter-frame predictor 118.

The intra prediction unit 117 performs intra frame prediction, and the inter frame prediction unit 118 performs inter frame prediction. These predictions are also called motion compensation.

The motion estimation unit 119 retrieves a reference frame for the macro block from the memory 116 and expresses a position difference between the image in the macro block of the retrieved reference frame and the image in the macro block of the current frame as a motion vector, Output to the first adder 112.

The entropy encoder 130 receives the control signal of the encoding controller 120, the motion data of the motion estimation unit 119, and the quantization data of the transform and quantization unit 113, and combines them to form an output bitstream. Create

The transform and quantization unit 113 converts and quantizes the difference data X corresponding to the bit depth N of the image data.

Hereinafter, the operation of the transform and quantization unit 113 will be described with reference to FIGS. 2 and 3.

2 is a block diagram illustrating a configuration of a transform and quantization unit 113 of an encoding apparatus according to an embodiment of the present invention, wherein the transform and quantization unit 113 may include a DCT transform unit 210 and a first divider ( 220, a first multiplier 230, a second divider 240, a second multiplier 250, and a shifting unit 260.

FIG. 3 is a flowchart for describing a converted light quantization process according to an embodiment of the present invention, in which step 310 is performed to convert difference data X into a frequency domain, according to hardware specifications according to bit depth N; Steps 320 to 350 for adjusting the size of the transformed difference data X and steps 360 to 370 for generating quantization data from the transformed and adjusted difference data X are included.

Referring to FIG. 3, look at the operation of the transform and quantization unit 113.

In general, since the difference data X is processed in a matrix form, the difference data X will be represented as a difference matrix X for convenience of explanation.

In operation 300, the transform and quantization unit 113 receives information about a bit depth N of an input image matrix.

In operation 310, the first adder 112 generates a difference matrix X by prediction of an input image matrix.

In operation 320, the DCT converter 210 generates a first matrix B by transforming the difference matrix X input from the first adder 112 to an integer DCT using Equation 1 below. For a block, the number and organization of the signal matrix is determined by the raw video format and the encoding mode of the macro block)

A = T

B = AT ^T

Where P and Q are matrix multiplications of the matrix P and matrix Q, T is an integer DCT transform matrix, T ^T is a transpose of the integer DCT transform matrix T, X is a differential matrix, and B is a DCT transformed product. 1 matrix.

For 8 ㅧ 8 DCT conversion, the integer DCT conversion matrix T is preferably the following matrix.

T = [8 8 8 8 8 8 8 8

10 9 6 2 -2 -6 -9 -10

10 4 -4 -10 -10 -4 4 10

9 -2 -10 -6 6 10 2 -9

8 -8 -8 8 8 -8 -8 8

6 -10 2 9 -9 -2 10 -6

4 -10 10 -4 -4 10 -10 4

2 -6 9 -10 10 -9 6 -2].

The DCT converter 210 outputs the integer DCT transformed first matrix B to the first divider 220 using the T matrix and the T ^T matrix.

In operation 330, the first divider 220 divides the converted first matrix B into a first predetermined value Shift Tab0 determined according to the bit depth N of the input image data, and divides the quotient. A second matrix C is generated by rounding to the nearest integer value. The generated second matrix C is transmitted to the first multiplier 230. Operation 330 may be represented by Equation 2 below.

C = B // Shift Tab0,

Where a // b divides a by b and rounds (approximates to the nearest integer).

 When the first multiplier 230 is implemented by a 16-bit multiplier, when the bit depth N of the input image data is 10 bits, the first predetermined value Shift Tab0 is set to 7. When the bit depth N is 12 bits, the first predetermined value Shift Tab0 is preferably set to 9. However, the first predetermined value Shift Tab0 may be set differently according to the specification of the multiplier implementing the first multiplier 230.

In operation 340, the first multiplier 230 coordinates the second matrix C with a predetermined matrix S having a predetermined coefficient s (i) and a domain-based array multiplication. D) is generated, and the third matrix D is transmitted to the third divider 240. Step 340 may be represented by Equation 3.

D = S. * C

Here, C is a second matrix, s (i) is a predetermined coefficient determined by the following equation (4), ". *" Operation means a coordinate-based array product.

P. * Q is an operation of multiplying each element of P with each element of Q at the same position as that element. According to an embodiment of the present invention, when the difference matrix X is an 8 ㅧ 8 matrix, the predetermined matrix S may be as follows.

S =

Each element s (i) of the predetermined matrix S is as follows.

/v(i), 여기서 i는 0 내지 5 사이의 정수이고, "≒"는 거의 동일한 값임을 의미한다. 즉, s(i)는

/v(i)와 오차 범위내에 있는 정수이다.s (i)

/ v (i), where i is an integer between 0 and 5, and "≒" means approximately the same value. That is, s (i) is

/ v (i) and an integer within the margin of error.

According to an embodiment of the present invention, v (i) has a value of v = [512 × 512, 442 × 442, 464 × 454, 512 × 442, 512 × 464, 442 × 464], and s (i) is s = [32768, 43969 39898 37958 36158, 41884].

We will now discuss the coordinate-based array product in detail. According to an embodiment of the present invention, a process of performing coordinate-based array multiplication of the second matrix C and the predetermined matrix S is as follows.

First, the data of the 0th or 4th row and the 0th or 4th column is multiplied by a preset coefficient s (0), and is any of the first, 3, 5, and 7th rows and is the first, 3, 5, 7th. Data in any one of the columns is multiplied by the predetermined coefficient s (1), and data in the second or sixth row and the second or sixth column is multiplied by the predetermined coefficient s (2). Moreover, data which is 0th or 4th row and is any one of 1st, 3, 5, and 7th row, and data which is 1st, 3rd, 5th, and 7th row and 0th or 4th column is predetermined coefficient s (3 Multiply by), and the data of the second or sixth row in the 0th or 4th row and the data of the 0th or 4th row in the second or 6th row are multiplied by the predetermined coefficient s (4), and the remaining data is multiplied by the predetermined coefficient s (5) Multiply by

Thereafter, the first multiplier 230 transmits the third matrix D generated by the coordinate-based array product to the second divider 240.

In operation 350, the second divider 240 divides the third matrix D by a second predetermined value Shift Tab1 determined corresponding to the bit depth N of the input image data, and divides the quotient of the nearest integer value. Approximation is performed to generate a fourth matrix (E). The generated fourth matrix E is transmitted to the second multiplier 250. Operation in operation 350 may be expressed as Equation 4 below.

E = D // Shift Tab1, where "//" is the same as in Equation 2.

When the second multiplier 250 is implemented by a 16-bit multiplier, when the bit depth N of the input image data is 10 bits, the second predetermined value Shift Tab1 is set to 17. When the bit depth N is 12 bits, the second predetermined value Shift Tab1 is preferably set to 15. However, the second predetermined value Shift Tab1 may be set differently according to the specification of the multiplier implementing the second multiplier 230.

When the difference matrix X generated in operation 310 is DCT transformed in operation 320, important values of the image data are collected into a specific portion. For example, meaningful values are collected when reconstructing image data in the upper left portion of the first matrix B generated by DCT conversion. In quantizing these values, in order to improve coding efficiency within limited hardware constraints, it is desirable to weight more important values to quantize important values at finer intervals, and quantize non-values at slightly less detailed intervals. In step 340, multiplying the predetermined coefficient s by multiplying a different scale factor for each data before extracting the quantized data from the transformed difference data X, so that important data can be quantized more precisely.

In addition, before and after the process of step 340, in the steps 330 and 350, a process of dividing data into first and second predetermined values determined corresponding to the bit depth is performed. This is a step of adjusting the data level in order to process the data with the extended bit depth under such a constraint because there is a limitation in hardware specification in quantizing the differential data X through a predetermined calculation process. Therefore, when the bit depth of the image data increases, in order to process this in a system having the same hardware specification, the operation is performed by dividing the DCT-converted first matrix B by a first predetermined value that increases in proportion to the bit depth. This is to prevent overflow from occurring in a multiplier, a memory, and the like, and to prevent loss of image data. The second matrix C divided by the first matrix B and the second matrix C generated by dividing the first matrix B by the predetermined coefficient s is divided by the second predetermined value, and the second predetermined value is the first predetermined value. In order to compensate for the redundancy caused by this increase, it is preferable to decrease in proportion to the bit depth as opposed to the first predetermined value. As such, it is preferable that the first and second predetermined values are appropriately adjusted according to hardware specifications so that no overflow occurs in a predetermined operation process for quantization. In addition, since the first predetermined value and the second predetermined value are appropriately adjusted according to the bit depth, the hardware can be utilized as efficiently as possible in a system having a fixed hardware specification to increase coding efficiency and improve image quality. You can get it.

Taking a specific numerical value as an example, in the conventional AVS encoding apparatus, when encoding conventional 8-bit video data, the first predetermined value is set to 5, but in the case of 10-bit or 12-bit video data, the first predetermined value. It is preferable to set this to 7 or 9. That is, in the case of using a 16-bit memory for input and output of the difference matrix (X), a 16-bit far plier for quantization, and a 32-bit Arithmetic Logic Unit (ALU) for a predetermined operation, a conventional 8-bit image is used. In the case of encoding data, the first and second predetermined values are set to 5 and 19, but when the bit depth is increased to 10 bits or 12 bits, the first and second predetermined values are set to 7, 17, or 9, respectively. Can be set to 15.

In operation 360, the second multiplier 250 multiplies the fourth matrix E by a predetermined coefficient q [QP] to generate a fifth matrix F. FIG. The fifth matrix F is transmitted to the shift unit 260. Operation in step 360 may be expressed as Equation 5 below.

F = q [QP] .E

Here, a.P means a scalar product of a and P matrix.

The predetermined coefficient q [QP] is determined as follows by the quantization parameter QP.

/

]q [QP] = round [

Of

]

Here, the quantization parameter QP is an integer between 0 ≦ QP ≦ 63,

round [X] is the integer closest to X.

The symbol "부" means that the value is approximately the same.

That is, q [QP] is determined according to the quantization parameter QP.

q [64] = {32768,29775,27554,25268,23170,21247,19369,17770,

16302,15024,13777,12634,11626,10624,9742,8958,

8192,7512,6889,6305,5793,5303,4878,4467,

4091,3756,3444,3161,2894,2654,2435,2235,

2048,1878,1722,1579,1449,1329,1218,1117,

1024,939,861,790,724,664,609,558,

512,470,430,395,362,332,304,279,

256,235,215,197,181,166,152,140}

Has the value of.

In operation 370, the shift unit 260 adds a predetermined value k to the fifth matrix F, and shifts the result to the right by 15 bits to generate the sixth matrix G. FIG. The sixth matrix G is transmitted to the entropy encoder 130 as quantized data. The predetermined value k is defined as follows.

*10/31For blocks in a frame, k = (1 << 15) * 10/31 =

* 10/31

*10/62For blocks between frames, k = (1 << 15) * 10/62 =

* 10/62

Here, << means left shift.

The reason for setting k differently according to intra-frame prediction and inter-frame prediction is that the characteristics of the difference matrix X are different for each prediction reason, and it is necessary to set different dead zones of the quantization unit.

Hereinafter, an apparatus and method for decoding N-bit image data according to the present invention will be described with reference to FIG. 4.

4 is a block diagram illustrating a configuration of an apparatus for decoding N-bit image data according to an embodiment of the present invention. The decoding control unit 420, the entropy decoding unit 430, and the inverse transform and inverse quantization unit 414 are illustrated. And a third adder 411, a deblocking unit 415, a memory 416, an intra-frame prediction unit 417, and an inter-frame prediction unit 418.

The entropy decoder 430 decodes the input bitstream to restore the control signal, the motion data, and the quantized data, and generates the control signal to the decoding controller 420 and the motion data to the interframe predictor 618. Are output to the inverse transform and inverse quantizer 414, respectively. The control signal includes information on a bit depth indicating the precision of the video data included in the input bitstream.

The decoding control unit 420 receives a control signal and controls the overall operation of the decoding apparatus.

The inverse transform and inverse quantizer 414 restores the differential data X by performing inverse integer DCT conversion on the quantized data received from the entropy decoder 430, and converts the restored difference data X 'into a third adder ( 411).

The third adder 411 adds the reconstructed difference data X 'and the predictive data predicted by the intra-frame predictor 417 or the inter-frame predictor 418, generates image data in units of blocks, and The result is output to the deblocking unit 415.

The deblocking unit 415 performs filtering on each reconstructed macroblock to reduce block distortion, and outputs each result of the filtering to the memory 416.

The memory 416 stores the data output from the deblocking unit 410 as reference data for later use by the intra-frame predictor 117 or the inter-frame predictor 118.

The intra-frame prediction unit 417 performs the intra-frame prediction, and the inter-frame prediction unit 418 performs the inter-frame prediction. These predictions are also called motion compensation. The interframe prediction unit 417 extracts a prediction macro block corresponding to the motion vector of the reference frame of the memory 416, compensates for the motion of the prediction macro block of the reference frame, and outputs prediction data.

FIG. 5 is a block diagram illustrating a more detailed configuration of the inverse transform and inverse quantization unit 414 shown in FIG. 4, according to an embodiment of the present invention. An inverse quantizer including a 510 and a third divider 520, a first transform unit 530, a fourth divider 540, a second transform unit 550, and a fifth divider 560. It includes an inverse transform unit including a.

6 is a flowchart illustrating an inverse transform and inverse quantization process according to an embodiment of the present invention, and includes an inverse quantization process of steps 600 and 610 and an inverse transform process of step 630. Hereinafter, a detailed operation of the inverse transform and inverse quantization unit 414 will be described with reference to FIGS. 5 and 6A.

In operation 600, the input bitstream is decoded to restore quantized data, that is, the sixth matrix G.

In operation 610, the first multiplier 510 multiplies r [QP] by the sixth matrix G received from the entropy decoder 430 to generate a seventh matrix H. Operation in step 610 may be expressed as Equation 6 below.

H = r [QP] .G,

Here, the quantization parameter QP is an integer between 0 ≦ QP ≦ 63,

이고, "."는 배열 곱을 의미한다.q [QP] * r [QP] =

And "." Means array product.

When q [QP] is the value mentioned in Equation 5 above, r [QP] has the following value.

r [64] = {32768,36061,38968,42495,46341,50535,55437,60424,

32932,35734,38968,42495,46177,50535,55109,59933,

65535,35734,38968,42577,46341,50617,55027,60097,

32809,35734,38968,42454,46382,50576,55109,60056,

65535,35734,38968,42495,46320,50515,55109,60076,

65535,35744,38968,42495,46341,50535,55099,60087,

65535,35734,38973,42500,46341,50535,55109,60097,

32771,35734,38965,42497,46341,50535,55109,60099}

n [64] = {14,14,14,14,14,14,14,14,

13,13,13,13,13,13,13,13,

12,12,12,12,12,12,12,12,

11,11,11,11,11,11,11,11,

10,10,10,10,10,10,10,10,

9,9,9,9,9,9,9,9,

8,8,8,8,8,8,8,8,

7,7,7,7,7,7,7,7}

In operation 620, the third divider 520 divides the seventh matrix H by n [QP], approximates the divided quotient to the nearest integer value, and generates the eighth matrix I. FIG. Operation 620 may be expressed as Equation 7 below.

I = H // n [QP], where "//" is the same as in Equation 2.

n [QP] is equal to the value mentioned in Equation 6.

In operation 630, the inverse DCT converter generates an twelfth matrix M by performing inverse DCT transformation on the eighth matrix I.

Hereinafter, a detailed process of step 630 will be described with reference to FIG. 6B.

In operation 632, the first transform unit 530 generates the ninth matrix J by multiplying the eighth matrix I by the transformation matrix T. Step 632 may be expressed as Equation 8 below.

J = IT

Here, T is an integer DCT conversion matrix used in the DCT converter 210 of FIG. 2.

In operation 634, the fourth divider 540 divides the ninth matrix J by 3 and approximates the division by the nearest integer to generate a tenth matrix K. FIG. Step 634 may be expressed as Equation 9 below.

K = J // 3

Here, "//" is the same as Equation 2.

In operation 636, the second transform unit 550 multiplies the ninth matrix K by T ^T to generate an eleventh matrix L. FIG. Operation of step 636 may be expressed as Equation 10 below.

L = ^T T · K

Where T ^T is the transpose of the integer DCT transformation matrix T.

In operation 638, the fifth division unit 560 divides the eleventh matrix L by 7 and approximates the divided quotient to the nearest integer value, thereby obtaining the twelfth matrix M, that is, the restored difference matrix X '. Create The operation of step 638 may be expressed as the following equation.

M = L // 7

Hereinafter, operations of the transform and quantizer 113 of the encoding apparatus and the inverse transform and inverse quantizer 414 of the decoding apparatus are as follows.

A = T

B = AT ^T

C = B // Shift Tab 0

D = S (i). * C

E = D // Shift Tab1

F = q [QP] .E

G = (F + k) >> 15

H = r [QP] .G

I = H // n [QP]

J = IT

K = J // 3

L = ^T T · K

M = L // 7

Here, the quantization parameter QP is an integer between 0 ≦ QP ≦ 63,

/v(i)이고(i는 0≤i≤5인 정수), s (i)

/ v (i) (i is an integer of 0≤i≤5),

v = [512 × 512, 442 × 442, 464 × 454, 512 × 442, 512 × 464, 442 × 464],

q [QP] ≒

이다.q [QP] * r [QP] ≒

to be.

Where a // b divides a by b, approximates the quotient divided by the nearest integer, PQ is a matrix multiplication of matrix P and matrix Q, aP is a scalar or array product of a and matrix P (array multiplication), P. * Q, is a domain-based array multiplication of matrix P and matrix Q, and a ≒ b means that a and b are approximately equal values.

At this time, the value of v (i) is determined according to the integer DCT transformation matrix T. If v (i) is determined, the value of s (i) is also determined. In addition, the first predetermined value Shift Tab0 and the second predetermined value Shift Tab1 may be set according to the specification of the multiplier for implementing the first multiplier 230 and the second multiplier 250, respectively. As a value that can be set differently, it is preferably set differently according to the bit depth.

7 is a graph illustrating a comparison of encoding efficiency between an encoding apparatus according to the prior art and an encoding apparatus according to the present invention using an RD curve. Referring to FIG. 7, the N-bit image data encoding / decoding apparatus and method according to the present invention have a capacity to encode N-bit data, and are modified to 10-bit or 12-bit by minimizing a conventional encoding apparatus. Not only the image data but also 14 bit image data can be encoded. At the same time, the encoding efficiency of the encoding apparatus is also improved, and the higher the PSNR, the more the improvement in the encoding efficiency is revealed more clearly than in the prior art.

The hardware specification of the conventional 8-bit encoder is as follows.

(1) The quantization parameter QP is in the range of 0 to 63.

(2) 16-bit memory is used for differential data input and output.

(3) A 16-bit muller is used for certain operations.

(4) Arithmetic Logic Unit (ALU) supports 32 bit operation.

Hardware specifications of the N-bit image data encoding apparatus according to an embodiment of the present invention are as follows.

(1) The quantization parameter QP is in the range of 0 to 63.

(2) 16-bit memory is used for differential data input and output.

(3) A 16-bit muller is used for certain operations.

(4) Arithmetic Logic Unit (ALU) supports 32 bit operation.

That is, according to the present invention, an N-bit image data encoding apparatus capable of encoding image data having various bit depths may be implemented by changing the encoding apparatus according to the related art to a minimum.

Although a preferred embodiment of the present invention has been described in detail above, those skilled in the art to which the present invention pertains may make various changes without departing from the spirit and scope of the invention as defined in the appended claims. It will be appreciated that modifications or variations may be made. Accordingly, modifications to future embodiments of the present invention will not depart from the technology of the present invention.

The apparatus and method for encoding / decoding N-bit image data according to the present invention, in the audio and video coding standard (AVS), quantize predictive difference data of input image data corresponding to a bit depth indicating the precision of image data, N bit image data having a bit depth can be processed, and encoding efficiency is improved. In particular, in quantization, since a predetermined operation is performed using a predetermined value that is variable in proportion to the bit depth, N having a variety of bit depths by modifying a coding / decoding system capable of processing only 8-bit image data at least. It can process bit image data.

Claims (20)

(a) generating difference data from prediction data of the image data, which is removed from the input image data; (b) converting the generated difference data into a frequency domain; And and c) quantizing the transformed differential data corresponding to a bit depth N representing the precision of the image data. The method of claim 1, wherein step (c) Performing a predetermined operation using predetermined coefficients determined according to the bit depth (N), thereby quantizing the transformed differential data. The method of claim 2, wherein step (c) (c1) dividing the transformed difference data into a first predetermined value; (c2) multiplying a result of dividing by the first predetermined value by a predetermined coefficient s; (c3) dividing a result of multiplying the predetermined coefficient s by a second predetermined value; (c4) multiplying a result of dividing by the second predetermined value by a predetermined coefficient q; And (c5) adding a predetermined value k to a result of multiplying the predetermined coefficient q, and shifting the result of adding the predetermined value k to the right of a predetermined bit, The first and second predetermined values are values determined corresponding to the bit depth, and step (c) is an integer operation. The method of claim 3, wherein the first and second predetermined values are When the bit depth N is 10, it is respectively 7 and 17, And 9 and 15 when the bit depth N is 12, respectively. The method of claim 4, wherein the first and second predetermined values are When the bit depth N is 10, it is respectively 7 and 17, And 9 and 15 when the bit depth N is 12, respectively. The method of claim 5, wherein when the difference data is 8 ㅧ 8 matrices, The predetermined coefficient s is s (i) = round [

/ v (i)], where i is an integer of 0 ≦ i ≦ 5, V (i) = {512 × 512, 442 × 442, 464 × 454, 512 × 442, 512 × 464, 442 × 464}, and v (i) is determined according to the conversion performed in step (b). N bit image data encoding method, wherein round [X] is an integer closest to X. The method of claim 6, wherein when the result of dividing by the first predetermined value is an 8x8 matrix, The step (c2) includes domain-based array multiplication of the matrix S and the matrix S as a result of dividing by the first predetermined value. The matrix S is

And the region-based array product is an operation of multiplying an element of the matrix S divided by the first predetermined value with an element of the matrix S at the same position. The method of claim 3, wherein the coefficient q is q [QP] = round [

Of

], Where QP is an integer of 0 ≦ QP ≦ 63, The constant k is k = round [

* (10/31)] or k = round [

* (10/62)], And the predetermined bit is 15 bits, wherein round [X] is an integer closest to X. The method of claim 1, wherein the encoding method and (d) generating a bitstream by encoding the information about the bit depth (N) and the quantized result, and outputting a bitstream. A difference data generator for generating difference data from which prediction data of the input image data is removed from the input image data; A converter for converting the generated difference data into a frequency domain; And And a quantization unit configured to quantize the transformed differential data in correspondence to a bit depth indicating the precision of the input image data. The method of claim 10, wherein the quantization unit A first divider dividing the converted difference data into a first predetermined value; A first multiplier for multiplying a result of dividing by the first predetermined value by a predetermined coefficient s; A second divider dividing a result of multiplying the predetermined coefficient s by a second predetermined value; A second multiplier for multiplying a result of dividing by the second predetermined value by a predetermined coefficient q; And A shifting unit for adding a constant k to a result of multiplying the predetermined coefficient q, and shifting the result of adding the constant k to the right of a predetermined bit, The first and second predetermined values are values determined corresponding to the bit depth N, And the operation performed by the first and second dividers is an integer operation. The apparatus of claim 10, wherein the encoding apparatus is And an entropy encoder configured to generate and output a bitstream by encoding the information about the bit depth (N) and the quantized result. (a) decoding the input bitstream and restoring quantization data and information about a bit depth N representing the precision of the image data included in the bitstream; (b) dequantizing the reconstructed quantized data corresponding to the bit depth; And and (c) restoring the differential data from which the inverse quantized result is inversely transformed into a time domain to remove the predictive data of the image data from the image data. The method of claim 13, wherein step (b) (b1) multiplying the reconstructed quantized data by a predetermined coefficient r; And (b2) dividing a result of multiplying the predetermined coefficient r by a predetermined coefficient n, The step (b) is N bit image data decoding method characterized in that performed by an integer operation. 15. The method of claim 14, wherein the coefficient r is r [QP] = round [

]ego, The coefficient n is n [QP] = 14-[QP / 8], wherein NP image data decoding method (wherein, QP is 0≤QP≤number, round [X] is an integer closest to X, [ X] is the largest integer of less than or equal to X). The method of claim 13, wherein the decoding method is and (d) restoring and outputting the image data by adding the predicted data of the image data to the reconstructed difference data. An entropy decoder configured to decode the input bitstream to restore information about a bit depth representing the precision of image data included in the bitstream and quantized data; An inverse quantizer for inversely quantizing the recovered quantized data corresponding to the recovered bit depth; And And an inverse transform unit which inversely transforms the inverse quantized result into a time domain to restore differential data. The method of claim 17, wherein the inverse quantization unit A third multiplier that multiplies the reconstructed quantized data by a predetermined coefficient r; And A third division unit dividing a result of multiplying the predetermined coefficient r by a predetermined coefficient n, And the operation performed by the third divider is an integer operation. 19. The method of claim 18, wherein the predetermined coefficient r is r [QP] = round [

]ego, Wherein the coefficient n is n [QP] = 14-[QP / 8], where QP is an integer of 0≤QP≤63, and round [X] is an integer closest to X , [X] is the largest integer less than or equal to X). A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 9 and 13 to 16.

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